CLEVELAND, Ohio -- The Indiana Pacers have in front of them a playoff opponent who they beat in three of four games this season.

No one's kidding themselves about it, though: The Pacers know playoff LeBron and playoff Cleveland Cavaliers are a whole different beast.

The No. 4 Cavs host the No. 5 Pacers in Game 1 of a first-round series Sunday.

"We all know the playoffs are a different ballgame," Pacers guard Darren Collison said.

The Cavs swept the Pacers out of the first round last season. Both teams have changed so dramatically since that series so in a sense, little can be taken from it.

Where that line of thinking stalls, though, is at the feet of LeBron James.

James, arguably the most dominant player in the first round of the NBA playoffs, has won 21 games in a row in the opening round (an NBA record). He's never lost a first-round series (12-0), nor even a Game 1 of any first round. The last time his team lost any game in the first round was May 6, 2012, when the Miami Heat lost by two to the New York Knicks in Game 4.

That series was over the next game.

"We do a great job of getting prepared," said James, who's averaging 29 points, 8.8 boards, and 6.9 assists in the first round. "And every team I've been on has always been prepared going into the first round of the postseason and I feel like we're well prepared again."

Paul George was the Pacers' best player last season. He was traded to Oklahoma City for Victor Oladipo, who is now Indiana's best player. He averaged career highs in points (23.1 per game), rebounds (5.2), and assists (4.3).

Domantas Sabonis was another key piece in the George trade. He's averaging 11.6 points and 7.7 boards, mostly off the bench.

Collison is Indiana's new point guard. He averaged 12.4 points and led the NBA with a .468 3-point field-goal percentage.

The Cavs' changes are even starker, perhaps because they've undergone two sets of them.

Cleveland traded Kyrie Irving last summer for Isaiah Thomas, Ante Zizic, Jae Crowder, and two draft picks. The Cavs also signed Derrick Rose and Dwyane Wade.

So if you're trying to glean anything for this series from what happened in the regular season, don't.

"They're moving the basketball, getting up and down the court a little quicker, they're shooting better as a team," Indiana forward Thaddeus Young said of Cleveland. "I think they're better with those things since the trades and they've got some really good pieces. But at the end of the day, they're still a beatable team."

James said "I don't have any concerns" about this series, though he said the Cavs and Pacers were the fourth and fifth seeds, respectively, for a reason.

"Both teams played good ball at times throughout the regular season," James said. "Obviously their season, from the outside looking in, was more productive than ours because of what they went through in the offseason. But we went through a lot in the offseason as well. It's a good matchup and we look forward to the challenge."

The Cavs have been to the last three NBA Finals, but have only four players (James, Kevin Love, Tristan Thompson, and JR Smith) left from the 2016 title team. Four players -- Cedi Osman, Zizic, Clarkson, and Nance -- have never played a playoff game.

And for the first time in his career, Love will be Cleveland's second scoring option in the playoffs instead of its third.

"We're going to be a tough team to beat in four games," Love said. "We have the best player in the world and a lot of guys that are hungry to go out and prove what they can do."